Дважды отрицательные среды на основе антиферромагнитных полупроводников для терагерцевого диапазона частот

The paper presents the results of a theoretical study of the dispersion characteristics of electromagnetic waves (EMW) existing in a transversely magnetized antiferromagnetic (AFM) semiconductor with loss. An AFM semiconductor is an infinite bi-gyrotropic medium, the effective material parameters of which are twice negative in several frequency ranges. It was found that these frequency regions are in the terahertz range and there are four backward EMEs in them, two of which are TE waves, and the other two are TM waves.

Current state and prospects of detectors in the terahertz range. Part 2. Heterodyne detection of terahertz radiation

The paper discusses the problems associated with the development of technology for terahertz radiation detectors. The main physical phenomena and recent progress in various methods of detecting terahertz radiation (direct detection and heterodyne detection) are considered. Advantages and disadvantages of direct detection sensors and sensors with heterodyne detection are discussed. In part 1, a number of features of direct detection are considered and some types of terahertz direct detection detectors are described. Part 2 will describe heterodyne detection and continue to describe some types of modern photonic terahertz receivers.

Thermally switchable terahertz metasurface absorber composed of H-fractal and enabled by phase-change material of vanadium dioxide

A terahertz metasurface absorber with actively switchable bandwidth enabled by vanadium dioxide (VO2) is presented and investigated numerically. The VO2 is a phase-change material and its conductivity in the terahertz range changes by several orders of magnitude upon phase-transition. The metasurface consists of an H-shaped fractal resonator placed on top of a polyimide spacer and a ground-plane of gold. The resonator is composed of an H-shaped level-1 fractal of gold and VO2 strips that converts it to a level-2 fractal. At room temperatures, the VO2 is in the insulator state and the resonator reduces to a level-1 fractal offering narrowband absorption at 8.08 THz reaching 0.98 absorption. At higher temperatures, the VO2 is in the metallic state and the resonator is effectively a level-2 fractal with an absorption higher than 0.9 in a bandwidth of 6.63–9.89 THz.